Beaten City confront W-League unknown

What happens when the team that's never lost, loses? And loses twice in a row?

Melbourne City's powerhouse W-League side are about to show us.

After the first perfect season in national soccer history and extending their winning run to 16 regular-season matches in this campaign, City have finally tasted that losing feeling.

A pair of 2-1 defeats to title fancies Canberra United and cellar-dwelling Western Sydney has turned the blowtorch on Joe Montemurro's side.

The club suffered a further blow when their championship-winning captain Lisa De Vanna jumped off the couch to sign for United for the balance of the season.

City midfielder and assistant coach Jess Fishlock said the club's fortnight had created cause for introspection but a response needed to come in their next match, a double header with Perth Glory on December 27.

"We can either feel sorry for ourselves or react together," she told AAP.

"Now we realise we're not going to step on the park and win. We have to earn the right to win.